"Fear the Walking Dead" star Mercedes Mason gave birth to son Caius Kane in January.

Mason and "The Office" star welcomed their first child together on January 10.

Denman shared the news on Instagram with a sweet photo and caption: "Happy and Healthy. Love this little man so much @mercedesmason is doing great. She a champ! #unmedicatedbirth We finally understand that love that no one can put into words. We're all on cloud 9."

She wrote: "Jack Adam Dykstra, we will talk about your tardiness eventually, but for now we've got a lot of love to give. Thanks to my besties for helping me laugh and smile and to my husband for just being my rock."

Olympian Michael Phelps and wife Nicole Johnson revealed the birth of son Beckett Richard on February 13, one day after he was born.

Phelps wrote: "Magical moments yesterday ... Nicole and I would like to introduce Beckett Richard Phelps to the world! We had a healthy baby boy and a healthy mama. I truly do feel like the happiest man in the world."

Johnson added that she's "surrounded by boys and I couldn't be happier."

Phelps and Johnson previously welcomed son Boomer in May 2016.

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"Breaking Bad's" Aaron Paul and wife Lauren Paul became first-time parents with the birth of Story Annabelle Paul.

Aaron and Lauren revealed the birth of the daughter in early February, and have gushed about their bundle of joy ever since.

"You can't imagine that you could love each other even deeper than you already do," Lauren told "Entertainment Tonight." "But I think it's just so cool, you know? We weren't blood-related before, but now there's this human that we're both related to and it makes us family in a new way, which I think is so special."

"We are blessed beyond measure with the arrival of our son, Gideon Martyn Forsyth," they told People in March. "Looking at our child for the first time was such an incredible moment! God is so good, and we are so thankful."

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"The Walking Dead's" Jeffrey Dean Morgan and Hilarie Burton revealed the birth of daughter George Virginia in early March.

In an emotional Instagram post, the "One Tree Hill" star opened up about the couple's many attempts to have a second child over the years.

Burton also explained why the couple kept her pregnancy quiet and waited to share the news of George's birth.

"When this pregnancy started, we were cautious," she wrote. "I didn't want to celebrate for fear of jinxing it. I didn't want a baby shower. I checked her heartbeat every day, up until the day she was born. And now that she is here, I just stare at her in wonder all day. I see her in her daddy's arms and I don't take any of it for granted. She screams bloody murder and I smile because she is so wildly alive."

"Entourage" star Perrey Reeves and Aaron Fox welcomed their first child in October 2017, but the news wasn't revealed until March 2018.

"I really didn't have any expectations so it is all amazing," Reeves told People in March. "Everyone tells you everything but you can't know until you are holding your baby in your arms. It really is the best. It is pretty incredible, she has changed so much in five months."

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Professional surfer Bethany Hamilton and Adam Dirks welcomed their second child, a son.

"We are overjoyed to welcome our son Wesley Phillip Dirks into the world! It's been a beautiful time getting life started with the four of us! We are thankful to God for our two lil guys!!!" Hamilton wrote on Instagram.

The couple previously welcomed their first child, son Tobias, in June 2015.

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In March, Fetty Wap and Lezhae Zeona welcomed their second child together.

Yes, this is his second child this year and he now has a total of seven children.
Jason Kempin/Getty Images

TLC stars Nate Berkus and Jeremiah Brent added a son to their family.

In March 2018, Berkus and Brent revealed the birth of their son, Oskar Brent-Berkus, via surrogate.

Taking to Instagram, Brent shared a photo showing daughter Poppy pointing to the newborn's foot and said that "life cracked open in a way I didn't think it could again."

He added: "Love multiplied. How can love continue to expand like this. Hand in hand our family is basking in the phenomenon of it all. We love you little Oskar. How thankful we are. How beautiful it all is."

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Kylie Jenner became a first-time mom after revealing the birth of daughter Stormi.

Country singer Jessie James Decker and NFL star Eric Decker welcomed their third child in March.

The couple took to Instagram to reveal the newest member of their family, a baby boy named Forrest Bradley Decker.

"Welcome to this world Forrest Bradley Decker! My heart is full! #wolfpack completed with a 9lb lean, eating machine (& a Decker bucket head)! Mommy sure knows how to grow some babies!!" Eric wrote on Instagram.

"Jersey Shore's" Ronnie Ortiz-Magro became a father for the first time with the birth of daughter Ariana Sky.

Since becoming a father, the reality TV star said that his perspective has changed.

"Things that were important to you just aren't important anymore," Ortiz-Magro told Us Weekly. "Your mindset is taking care of your family and being a good role model and basically just, you never want to see anything happen to them."

Meyers explained that Ashe gave birth before they could reach the front door of their apartment building and make their way to the hospital — but thankfully the birth went smoothly with the help of firefighters, neighbors, the NYPD, and the EMT.

Rachel McAdams and Jamie Linden reportedly welcomed a baby boy.

McAdams and Linden were first seen together in 2016.
Brian de Rivera Simon/Getty Images

According to a report from People, the "Disobedience" star and her boyfriend welcomed their first child together. The report was released after Linden and McAdams were photographed in public, with Linden holding a baby in his arms.

Dwayne "The Rock" Johnson and Lauren Hashian revealed the birth of daughter Tiana Gia in April.

"If you really want to understand the single most powerful and primal moment life will ever offer, watch your child being born. It's a life-changer and the respect and admiration you have for a woman, will forever be boundless," Johnson wrote.

He added: "Your crazy dad has many responsibilities and wears many hats in this big ol' world, but being your dad will always be the one I'm most proud to wear."

"Ladies, it's okay that our bodies are not PERFECT after our babies are born," she wrote. "Give yourself time. Go at your own pace. Don't allow people to put a time limit on YOUR body. You've just accomplished a miracle!"

Mowry-Hardrict and Hardrict previously welcomed their first child together, son Cree, in 2011.

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Kirsten Dunst and Jesse Plemons reportedly welcomed their first child.

"They [Blake Lively, Alexis Bledel, and Amber Tamblyn] are a go-to for me, just one message away and I ask them a million questions," Ferrera told Us Weekly. "Everything from trying to wrap my mind around the actual birth to talking about what their experiences were and what to prepare for."

Duff's family now includes two children, following the birth of daughter Lulu Gray on June 5, 2018. The actress revealed the news with a sweet Instagram post that showed their older child cradling with new bundle of joy.

Golden State Warriors player Stephen Curry welcomed his third child with Ayesha Curry.

The athlete and the cookbook author took to Instagram to reveal the birth of son Canon.

"My heart is FULL," Ayesha wrote. "God has been too good to us. Our beautiful baby boy Canon W. Jack Curry 7/2/2018. He joined us earlier than we thought and we couldn't be more excited and grateful. Family of 5!"

The Currys previously welcomed daughters Riley and Ryan in 2012 and 2015.

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"I Feel Pretty" actor Tom Hopper and his wife welcomed their first second together.

Tom Hopper also appeared on HBO's "Game of Thrones."
Frazer Harrison/Getty Images

"Where there were three Stagliano's, now there are four! Whahooo! Welcome to the world Hunter James. Oh also @emilystag is a powerhouse of a Mom! So proud of her and SO in love with her," he wrote online.

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Former WWE star Stacy Keibler and Jared Pobre expanded their family with the arrival of son Bodhi Brooks.

Stacy Keibler and Jared Pobre have been married since 2014.
Chelsea Lauren/Getty Images for Ciroc

Taking to Instagram, Christensen revealed what happened when she was assisted by husband Cole Maness as she gave birth.

"It will go down in family history because baby girl's own, incredible dad delivered her all by himself," she wrote. "My fault, as I didn't know she would come so quickly and didn't call the doc until far too late. He came straight over and arrived about one minute after she joined us in the world."

Weisz and Craig are no strangers to parenting — they both have children from previous relationships. The "My Cousin Rachel" actress has a son named Henry with director Darren Aronofsky while Craig has a daughter named Ella with Fiona Loudon.

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Rashida Jones reportedly became a mother with the birth of a son named Isaiah Jones Koenig.

"To the people who have protected us and kept our growing family safe and respected our privacy. To our tribe for expanding with grace and exponential amounts of love. To my @halfadams for being so supportive during every moment of my pregnancy and her birth. And to whatever incredible force of fate that brought this baby girl into our lives," she wrote.

The actress added: "I couldn't be more proud to be her mother. To bring a new girl into this world and to do my best to raise her to be kind, strong and whatever the heck she wants to be."

Adams echoed her sentiments, writing: "We will raise her to be powerful, to always speak her mind and heart and to live without fear. It's a brand new day and a brave new world and they are both beautiful."